Getter supporting structure



Sept. 19, 1950 u. HAMVAS 2,523,016

GETTER SUPPORTING STRUCTURE Filed Dec. so. 1948 Lm 20 a Q I 1 /8\ 1 1 l7 l W m 1 Inventor:

Laszl 0 U. Hamvas,

by M A M His Attorneg.

UNI-TED STATE Patented Sept. 1 9 1950 S EN OFFICE GE'l-TER SUPPORTING STRUCTURE Laszlo U. Hamvas, Schenectady, N, Y., assignor to General Electric Company, a corporation of New York Application December 30, 1948; Serial No. 68,098

After an electron discharge device has been mechanically exhausted, a getter material such as; barium is. usually flashed or vaporized within the deviceto clean up theresidual gas molecules. l t: is desirable to controlthe flashing of the getter by heating it. separately with respect to the other elements of the discharge device, this being usually accomplished by passing a heating current through a. getter holder consisting of a conducting strip or' tubing onor in which the getter materiah is placed. In discharge devices having a glass envelope the heating current may be induced in. a. short-ci'rcuited getter circuit within the envelope by a high: frequency induction coil which is: outside ofv the discharge device envelope. An advantage of. this method of flashing the getter isathei resulting simplicity of the discharge device itself, as the: getter circuit is entirely self-contained and no. external terminals are needed.

In. apparatus of the character specified, it has been a common practice to form the closed getter circuit: by welding a getter holder strip or tubing across the open ends of a U-shaped wire or an incomplete. circular wire ring. The loop so formed is customarily" Welded at one point to the top shield or' to a separate supporting element in the electron discharge device to hold the loop in position. The remainder of the getter loop must be spaced from the mount assembly. A disadvantage encountered when the getter loop is welded at one point to the top shield is the lack the supports.

of'anexact predetermined location and position of -the getter loop. If this disadvantage is overcome by the use of additional supporting parts or special methods tofiposition the getter loop, the cost. of manufacturingthe discharge device may thereby be" increased;

is an object of my invention to provide a simplified getter loop structure which utilizes an existing discharge device element as part of the getter loop circuit and thus reduces the. cost of manufacture.

A feature of the invention which is useful inventing the deposition of stray getter material.

from the getter holder on the electrodes belo theshield'.

Another aspect of the invention is the integral connection of the getter supports to the top shield, the supports being most easily formed bypunching them as tabs when the shield blank is manufactured and bending up the tabs to form This construction results in a sim-- plified assembly, since no separate getter loop is required, and the getter may be readily assembled in a predetermined position because of the predetermined. location of the getter supports;

In another embodiment of my invention which is also useful in fulfilling the foregoing object, I supply a pair offgetter supporting strips which are fastenedto the edges of the anode in a discharge device of the stacked electrode type, the anodebeing the uppermost electrode and serving also to shield those electrodes below it from the" effects of getter material deposition. The getter holder; is fastened to the support strips, formingwiththe supports and the anode a short-circuited electrically conductive path. The supports are of sufficiently small cross section and of sufficient length to conduct a relatively small amount of heat to the getter from the anode and the other parts of the electrode assembly. By reason of their predetermined location, the getter holdermay be easily assembled in the correct position.

The features which I desire to protect herein are pointed out with particularity in the appended claims. The invention itself, together with further. objects and advantages thereof, may be best understood by reference to the following description, taken in connection with the drawings in which Fig. 1 isa view partly in cross section showingan electron discharge device embodying my invention; Fig. 2 is an enlarged perspective view of the getter supporting shield shown in Fig. 1; and Fig. 3 is a view. partly in cross section showing an electron discharge device embodying. a modification of my invention.

Referring now to Fig-1, there is shown. an electron. discharge device of a type commonly used. in radio receiving tube circuits. As illustrated, an envelope. l of glass or other suitable vitreous material surrounds. an electrode assembly having a plurality of lead-in conductors 2' sealed through the lower end of the envelope. The electrode assembly includes a cathode 3', a grid' l, and-an anode 5, and further electrodes maybe present asis: common'in discharge devices: of this type. As. further shown, a conventional. mica spacer 6' holds the upper ends of. electrodes 3, 4, and 5 and support rods. 1' in a fixed space relationship. Above the: top spacer is a. metallic shield 8, fastened to the support rods 1 tohold it. in place.v The shield has a horizontal portion 9 and a vertical portion I which are employed in a conventional manner to electrically shield the upper ends of electrodes 3, 4, and 5.

According to my invention and as shown in detail in Fig. 2, two narrow metallic tabs 12 at opposite edges of the horizontal shield portion 9 are bent up vertically and have further end portions l3 bent over horizontally toward each other. The getting holder I4 is positioned on the supporting tabs and its ends welded to portions I3 to hold it securely in place and to form a good electrical connection. The shield may be easily formed by punching out a blank of sheet'nickel or other suitable material and bending up the tabs l2 with respect to the horizontal portion 9, further bending over the flanges l3 at the ends of the tabs I2, bending down a portion of this shield to form a vertical shielding portion [0, and bending the ears I lsuitably to facilitate connection to the mount support rods 1. The tabs I2 have a relatively small cross section and are long enough, as illustrated, so that they do not conduct a substantial amount of heat from the electrode assembly to the getter material. I have found that a thin nickel sheet material about .005 inch thick has adequate mechanical strength for this purpose and at the same time its thinness prevents heat conduction from being a problem with respect to premature flashing of the getter.

The getter holder I have shown in Fig. 1 is a strip [4 of conducting metal which, because of its long narrow shape, presents a sufflcient resistance to the flow of the induced current to heat the strip to a high temperature along its entire length. A central depressed portion [5 extends almost to the ends of the strip and accommodates an adequate amount of a conventional getter material [6, such as barium or a barium salt mixed with a reducing agent. Of course my invention is not limited to the use of the getter holder illustrated, but obviously includes other getter holders, such as those consisting of a length of iron tubing containing a getter material and clamped together at its ends. In this tubular type of getter holder, as commonly used in the art, a thin portion in the tubing wall bursts when the getter is flashed and the remaining trough, like the recessed holder strip [4 shown in Fig. 1, constitutes a getter shield between the getter and other elements of the tube.

The completed getter supporting structure, without further components, is a short circuited electrically conductive loop, the getter holder [4, the tabs 12, and the shield portion 9 constituting the circuit. After the discharge device is assembled and exhausted a high frequency current is induced in the closed getter circuit by conventional means. The induced current heats the getter holder to a temperature suflicient to start the desired reaction or vaporization of the getter material. The horizontal portion 9 of shield 8 also serves to prevent the deposition of getter material upon the electrodes below it in addition to the usual shielding function of the getter holder itself.

'In' Fig. 3 is shown another discharg device having a glass envelope IT with vertically stacked electrodes, the anode I8 being the uppermost electrode in the stock. Annular ceramic disks l 9 are used tolspace the anode and other electrodes from each other. In this embodiment of my invention I employ a pair of sheet metal supports 20 which are welded to the outer edge of the anode I8 at their lower horizontal ends and are separated from each other by the diameter of the anode. The supports 29 extend above the stacked electrode assembly into the space between the mount assembly and the top of the envelope. A getter holder 2! is welded to the upper ends of the getter supports l9, thus constituting a short circuited electrically conductive loop consisting of the anode l8, the supports 20, and the getter holder 21. It is obvious that, without departing from my invention, that the getter supports 20 may be integrally combined with the anode as tabs on the anode blank.

The getter is flashed as described for the embodiment illustrated in Fig. 1 save that the getter circuit is completed through the anode rather than a shield member. The anode in this embodiment also serves to shield the electrodes below it from efiects of stray getter deposition.

In using the term elements, I means to include both electrodes, such as anodes, and also shields which may or may not serve as electrodes. I recognize, of course, that an electrode such as the anode may also function as a shield.

While the present invention has been described in reference to particular embodiments thereof, it will be understood that numerous modifications may be made by those skilled in the art without actually departing from the invention. I, therefore, aim in the appended claims to cover all such equivalent variations as come within the true spirit and scope of the foregoing disclosure.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In an evacuated electron discharge device of the type having a vitreous envelope enclosing a plurality of metallic elements, one of said metallic elements constituting an electrical shield for other of said elements, a pair of metallic arms secured to said one of said elements and positioned between said one element and said envelope, and a metallic getter holder connected to said arms and extending therebetween to form therewith and with said one element a shortcircuited electrically conductive path, said arms forming paths of low thermal conductivity between said getter holder and said one of said elements.

2. In an evacuated electron discharge device of the type having a vitreous envelope enclosing a plurality of elements including cathode, grid, and anode electrodes and having a plurality of lead-in conductors sealed through the lower end of the envelope, a metallic electrical shield supported in position above the upper ends of said electrodes, a panel tabs integral with said shield REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,883,174 Von Wedel Oct. 18, 1932 1,924,266 Wienecke Aug. 29, 1933 Lederer Sept. 19, 1939 

